Description

Materials that sample the scene depth map via screenDepthPS were decoding it in the wrong format on textureFloatRenderable devices, producing garbage depth values (visible as zebra/banding artifacts on any geometry shaded against scene depth — e.g. a gsplat cutout effect, and StandardMaterial paths that read uSceneDepthMap).

Root cause

screenDepthPS selects its decode from two defines:

#ifdef SCENE_DEPTHMAP_LINEAR
    #ifdef SCENE_DEPTHMAP_FLOAT
        return texture2D(uSceneDepthMap, uv).r;   // R32F: read float directly
    #else
        // unpack a float from RGBA8 ...
    #endif
#endif

Material shaders assemble their defines through ShaderUtils.getCoreDefines, which copies cameraShaderParams.defines. CameraShaderParams can only ever emit SCENE_DEPTHMAP_LINEAR — it has no device reference, and SCENE_DEPTHMAP_FLOAT depends on device.textureFloatRenderable. So the material path never set SCENE_DEPTHMAP_FLOAT.

Meanwhile RenderPassPrepass allocates the linear-depth texture as R32F when device.textureFloatRenderable (and packed RGBA8 otherwise). On a float-renderable device the texture is therefore R32F, but the material shader took the packed-RGBA8 decode branch → wrong values.

The post-process passes (render-pass-taa, render-pass-coc, render-pass-ssao, render-pass-depth-aware-blur) each already work around this by calling ShaderUtils.addScreenDepthChunkDefines(device, ...) themselves. The material define path was the one place that didn't.

Fix

Call ShaderUtils.addScreenDepthChunkDefines from getCoreDefines (which already has params.device in scope), so materials get SCENE_DEPTHMAP_FLOAT whenever the device is float-renderable — matching the format the prepass allocated. The redundant SCENE_DEPTHMAP_LINEAR re-set is a no-op (same key/value).

Fixes #

Checklist

• I have read the [contributing guidelines](https://github.com/playcanvas/engine/blob/master/.github/CONTRIBUTING.md)
• My code follows the project's coding standards
• This PR focuses on a single change